Who studies philosophy?

This is a quote from the late Robert Solomon in a lecture on Kierkegaard:

There’s a comment in Nietzsche which I’ve always found extremely revealing, and, of course, many people believe this, especially if they’re not philosophers. But what a philosopher tends to argue, however abstract or abstruse it might be…what a philosopher tends to argue typically has to do with his or her personal problems. There’s a sense in which philosophy is personality rendered explicit is some rather difficult words. (Robert Solomon from lecture 7 ‘No Excuses’)